(19)
(11) EP 0 210 640 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
21.06.1989 Bulletin 1989/25

(43) Date of publication A2:
04.02.1987 Bulletin 1987/06

(21) Application number: 86110429.7

(22) Date of filing: 29.07.1986
(51) International Patent Classification (IPC)4: G06F 13/10
(84) Designated Contracting States:
DE FR GB

(30) Priority: 31.07.1985 JP 170430/85

(71) Applicant: HITACHI, LTD.
Chiyoda-ku, Tokyo 100 (JP)

(72) Inventors:
  • Tanaka, Shunji
    Machida-shi (JP)
  • Umeno, Hidenori
    Tsukui-gun Kanagawa-ken (JP)

(74) Representative: Strehl Schübel-Hopf Groening & Partner 
Maximilianstrasse 54
80538 München
80538 München (DE)


(56) References cited: : 
   
       


    (54) Input-output control system in a virtual machine system


    (57) An I/O control system in a virtual machine system has at least one virtual machine (VM) running under control of a virtual machine control program (VMCP) and has a direct I/O execution mode in which an I/O interruption to the I/O device dedicated by the running VM is directly executed without intervention of the VMCP and an indirect I/O execution mode in which the I/O interruption is simulated. The I/O control system comprises identification portion for identifying the I/O device requesting the switching to the direct I/O execution mode, judge portion (Figures 1a and 1c) for judging a mode switching condition and mode selection portion (Figures 1 b and 1d) for selecting one of the two modes. If the VM which contemplates the direct execution has not yet dedicated the I/O device requesting the mode switching, it dedicates the I/O device, and if the VM has not yet dedicated an 1/0 interrupt subclass which controls the I/O interruption of the I/O device, it dedicates the subclass, and the I/O device in the indirect I/O execution mode is switched to the direct I/O execution mode.






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